1. Field of the Invention
This invention relates generally to pump systems, and more particularly, to a four-head diaphragm pump arrangement that is particularly suited for use in portable medical devices, such as a ventricular assist system.
2. Description of the Related Art
Ventricular assist devices are life sustaining systems that preferably are sufficiently portable to be carried by a patient without undue weight or bulk. Preferably, such a system should be powered by compressed air, notwithstanding that compressed air in such an application would require that a significant head pressure be overcome. Although other gases of lower density would function in this application with reduced head pressure, such would require the use of a compressed gas stored in heavy tanks to supply the implanted blood pump of the ventricular assist device. The preferred gas therefore it is filtered room air, as it is readily available in an unlimited supply, and provides the additional safety aspect to the patient of not requiring the use of tanks that can lose pressure or run empty at inopportune times.
An air pump for the ventricular assist device application needs to be compact, light in weight, low in vibration, and electrically efficient. In addition, it is highly desirable that the pump arrangement to be quiet in its operation, and particularly that the noise at the intake be maintained at a minimum to eliminate the need for cumbersome muffler systems. Intake air noise is a major contributor to overall sound output. Finally, it is essential that the pump arrangement to be reliable, and that it operate at reduced temperatures to achieve an extended lifespan. It is often desirable to maintain the maximum operating temperature of a device that will contact human skin to below 40° C.
It is, therefore, an object of this invention to provide a battery powered air pump arrangement that is suited for powering a portable ventricular assist device.
It is another object of this invention to provide an air pump arrangement that operates quietly and pneumatically efficiently.
It is also an object of this invention to provide an air pump arrangement that operates with minimal vibration.
It is a further object of this invention to provide an air pump arrangement that operates electrically efficiently.
It is additionally an object of this invention to provide an air pump arrangement that is reliable with redundant subsystems and can achieve powering of a ventricular assist device to a life-sustaining degree notwithstanding at least one subsystem failure.
It is yet a further object of this invention to provide an air pump arrangement that can achieve powering of a ventricular assist device to a heart rate of approximately 180 beats per minute.
It is yet an additional object of this invention to provide an air pump arrangement that can achieve low vibration powering of a ventricular assist device over a broad range of a heart rate, illustratively between approximately 40 to 180 beats per minute.
It is also another object of this invention to provide an air pump arrangement that can achieve inflation of a ventricular assist device in approximately 150 ms.